1. Field of the Invention
This invention relates to devices for raising anchors from the bottom of a body of water to the surface of the water, and more particularly to devices that raise anchors by means of buoyancy created by inflating part of the device with air.
2. Related Art
Some methods for using inflated bags to lift anchors or other objects to the surface of a body of water are known in the prior art. For example, Spickelmire (U.S. Pat. No. 5,373,801) discloses a method using a float and the movement of a boat to lift a submerged object. A rope is tied to the submerged object and passed through a device attached to the float that allows movement of the rope only in one direction. The rope is then connected to the boat. The boat is driven away from the float in order to pull the rope through the one-way device. Once the submerged object is raised, the float and object may be pulled into the boat.
Holmes (U.S. Pat. No. 5,690,047) discloses a float attached to an anchor that is remotely inflated. The float is connected to an air pressure generator on the surface via a flexible conduit that is generally coextensive with the line or cable used to raise or lower the anchor. The Holmes float surrounds and is coaxial with the rod of the anchor, so that the float is generally a “dough-nut”  shape around the anchor directly above and closely adjacent to the “prongs” of the anchor. The air hose extends along the anchor rope and is clamped to the anchor rope.
In some situations, it may be inconvenient or even impossible to use a device such as Spickelmire's because there is insufficient available space to use the boat to lift or because it would require rowing a small watercraft upstream. The Spickelmire device is particularly impractical for rivers or crowed bodies of water where there is little room for the boat to maneuver or travel. Holmes device would tend to become compacted around the anchor prior to inflation, which creates a risk that a hard object such as a rock could become lodged between the float and the anchor adding weight and possibly puncturing the float. Also, the hose is clamped to the rope making it subject to the tension between the boat and anchor, which it is not capable of handling. Thus, there is a need for an improved buoyant anchor-lifting mechanism.